Question

Plane polarised light is passed through a polaroid. On viewing through the polaroid; we find that when the polaroid is given one complete rotation about the direction of the light, one of the following is observed

• A. the intensity of light gradually decreases to zero and remains at zero
• B. the intensity of light gradually increases to a maximum and remains at maximum
• C. there is no change in intensity
• D. the intensity of light is twice maximum and twice zero

Answer 1

Answer: (D)

During rotation $\to$
When $\theta =0^{\circ }$ Intensity goes to maximum
When $\theta =90^{\circ }$ Intensity becomes zero
When $\theta =180^{\circ }$ Intensity become maximum again
When $\theta =270^{\circ }$ Intensity again become zero.
Where $\theta$ is the angle of rotation.